Проверка электронной почты с использованием JavaScript не работает в статусе if

const form = document.getElementById('form');
const email = document.getElementById('email');

form.addEventListener('submit', (e) => {
  e.preventDefault();
  checkInputs();
})

function checkInputs() {
  const emailValue = email.value;
  const emptyEmail = emailValue === '';
  const invalidEmail = !isEmail(emailValue);
  email.parentElement.classList.remove('success');
  if (emptyEmail) {
    setErrorFor(email, 'Oops! Please add your email');
  } else if (invalidEmail) {
    setErrorFor(email, 'Oops! Please check your email');
  } else {
    setSuccessFor(email);
  }
};

function setErrorFor(input, message) {
  const formGroup = input.parentElement;
  const small = formGroup.querySelector('small');
  formGroup.className = 'form-group error';
  small.innerHTML = message;
}

function setSuccessFor(input) {
  const formGroup = input.parentElement;
  formGroup.classList.add('success');
}

// checks if email is valid
function isEmail(email) {
  const regx = /^(([^<>()\[\]\\.,;:\s@"]+(\.[^<>()\[\]\\.,;:\s@"]+)*)|(".+"))@((\[[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}])|(([a-zA-Z\-0-9]+\.)+[a-zA-Z]{2,}))$/;

  return regx.test(email);
}

.success { background-color:green }

<div class = "form-group">
  <form id = "form" method = "POST" name = "subscribe">
    <input type = "email" placeholder = "Email address" name = "email" id = "email" class = "email-input error">
    <br>
    <small></small>
    <br>
    <button class = "form-btn" type = "submit">Request Access</button>
  </form>
</div>